Question

Two light bulbs have resistances of 40 2 and 802. The two light bulbs are now connected in parallel across the 12 V supply. Find the current through each bulb. Express your answer in amperes separated by a comma. VASO 140, 180 = A Submit Request Answer Part E The two light bulbs are connected in parallel across the 12 V supply. Find the power dissipated in each bulb. Express your answer in watts separated by a comma. LOAD ? P40, P80 = W Submit Request Answer Part F The two light bulbs are connected in parallel across the 12 V supply. Find the total power dissipated in both bulbs. Express your answer in watts. ΠΙ ΑΣΦ ? P = w

Answer 1

Resistance of 1^st bulb, R1 = 40 Ω

Resistance of 2^nd bulb, R1 = 80 Ω

Total resistance of the bulbs when they are connected in parallel,

R = R1 R2/(R1 + R2) = 40 x 80/(40+80) = 26.7 Ω

Voltage supplied to the combination of bulbs, V = 12 V

i.

total current drawn from the battery, I = V/R = 12/26.7 = 0.45 A

current trough the 1^st bulb, I1 = V/R1 = 12/40 = 0.30 A

current trough the 2^nd bulb, I2 = V/R2 = 12/80 = 0.15 A

ii.

power dissipated in the 1^st bulb, P1 = I1²R1 = 0.30 x 0.30 x 40 = 3.6 W

power dissipated in the 2^nd bulb, P2 = I2²R1 = 0.15 x 0.15 x 80 = 1.8 W

iii.

total power dissipated in both bulbs, P = P1 + P2 = 3.6 + 1.8 = 5.4 W